Stereotactic Radiosurgery For Acoustic Neuroma Research Articles

Correlation between initial tumor enlargement and magnetic resonance imaging characteristics following linear accelerator-based stereotactic radiosurgery for acoustic neuromas.

Initial tumor enlargement (or pseudoprogression) instead of true tumor progression is acommon phenomenon in patients with acoustic neuromas who are treated with stereotactic radiosurgery (SRS). This phenomenon can affect clinical decision-making and patient management. This study assessed the correlation between initial tumor enlargement and magnetic resonance imaging characteristics in patients with acoustic neuromas who were treated with linear accelerator (LINAC)-based SRS. The long-term tumor control outcomes were also analyzed. In total, 330 patients with sporadic acoustic neuromas who were treated with LINAC SRS between March 2006 and March 2020 were retrospectively evaluated to assess their initial tumor enlargement. The tumors were divided into homogeneously enhanced, heterogeneously enhanced, and cystic types based on the morphological characteristics noted on magnetic resonance images. Tumor control was assessed in 275 patients with afollow-up duration of more than 2years. Initial enlargement was observed in 137 of 330 (41.5%) tumors as early as 3months after LINAC SRS. Data analysis revealed that postoperative tumors with aresidual volume lower than 2.5 cm3 had alower incidence of initial enlargement (p = 0.039). No correlation was noted between the initial enlargement and morphological characteristics of tumors. In patients with amean follow-up duration of 82.8 ± 37.2months, heterogeneously enhanced tumors exhibited alower control rate than homogeneously enhanced and cystic tumors (p = 0.045). No correlation was noted between initial enlargement and tumor control. Initial enlargement can occur as early as 3months after SRS. Postoperative residual tumors with avolume lower than 2.5 cm3 exhibit alower incidence of initial enlargement. Heterogeneously enhanced tumors have alower local control rate.

Cognitive and psychosocial outcomes following stereotactic radiosurgery for acoustic neuroma.

Acoustic Neuroma (AN) is a benign tumour of the eighth cranial nerve. Stereotactic Radiosurgery (SRS) is a common treatment approach. Studies have explored the primary effects of SRS and documented equivalent efficacy for tumour control compared to neurosurgery. Examine the longer term cognitive and psychosocial outcomes of SRS in non-Neurofibromatosis Type II patients utilising both objective and subjective cognitive outcomes associated with quality of life and health related distress. Nineteen individuals treated via SRS were assessed using a battery of standardised psychometric tests as well as measures of quality of life and psychological distress. Participants had largely preserved cognitive function except for processing speed, aspects of attention and visual memory relative to age norms. Self-reported quality of life was better than in other AN population studies. Level of psychological distress was equivalent to general population norms. More than half of participants reported subjective cognitive decline though this was not fully supported by objective testing. Subjective cognitive complaints may be associated with lower reported quality of life. Results are largely consistent with previous findings on the effects of SRS in other clinical groups, which supports SRS as a targeted radiation treatment for AN.

Long-Term Quality of Life and Audiometric Outcomes Following Noninvasive Stereotactic Radiosurgery for Acoustic Neuromas

Though microsurgery remains the most common method for management of acoustic neuromas (ANs), stereotactic radiosurgery continues to be a promising alternative. This study assesses long-term quality of life (QOL) outcomes and changes in hearing acuity in patents who have undergone single fraction Gamma Knife stereotactic radiosurgery (GKSRS) for AN.Prospective QOL outcomes were collected and analyzed to include Hearing Handicap Inventory (HHI), Dizziness Handicap Inventory (DHI), Tinnitus Handicap Inventory (THI), and 36-Item Short-Form Survey (SF-36) scores. Likewise, audiometric outcomes including speech discrimination (SD) and pure-tone average (PTA) were assessed. These data points were collected prior to and following GKSRS at regular intervals up to 5 years post-treatment. A mixed effects model for repeated measures was employed to assess QOL data for statistical significance.A total of 235 patients underwent GKSRS for AN at our institution from January 2007 to January 2017. Of these, 130 patients had available QOL and audiometric follow-up data and were included in this study. Median age was 60 y and median follow-up time was 36 mo. Median tumor size was 1.6 cm (0.1 - 3.6 cm), with median tumor volume of 0.552 cm3 (0.028 - 11.31 cm3), while median cochlear mean dose was 2.4 Gy (0 - 9.7 Gy). Baseline mean (median) HHI, DHI, THI, and SF-36 scores were 31.7 (28), 19.3 (12), 18.2 (12), and 70.0 (73.4) respectively. For each of these QOL metrics, mixed effects analysis indicated no statistically significant decline at any time point out to 5 years post-treatment. Indeed, 87% of patients had baseline SD and PTA scores available; 70% had follow-up SD and PTA available. Of these, 59% had baseline serviceable hearing (Gardner-Robertson score of I or II). Serviceable hearing was preserved in 71% of patients at 1 month, 79% at 6 months, 79% at 12 months, 62% at 18 months, 67% at 24 months, and 68% at 36 months.GKSRS provides long-term maintenance of QOL in the treatment of AN. HHI, DHI, THI, and SF-36 scores showed no significant decline up to 5 years post-radiosurgery. Patients with baseline serviceable hearing exhibited adequate hearing preservation.J.S. Lee: None. K.C. Lee: Royalty; Regents of the University of Michigan. Patent/License Fees/Copyright; Regents of the University of Michigan. D. Bojrab: None. P.Y. Chen: Stock; Greater Michigan Gamma Knife (GMGK). J. Jacob: None. I.S. Grills: Greater Michigan Gamma Knife.

P19.02 Clinical and radiological long term outcome of acoustic neuromas (Koos grade I - IV) after stereotactic radiosurgery

AbstractIntroduction:In the management of acoustic neuroma (AN) stereotactic radiosurgery (SRS) has evolved as widely accepted treatment option for small-sized tumors (Koos I and II). For larger AN (Koos III and IV) microsurgery is treatment of choice. However, for patients not suitable for microsurgery SRS might also be an alternative that balances tumor control, hearing preservation and adverse effects. The purpose of this analysis was to evaluate the efficacy and toxicity of SRS for different Koos grades including AN Koos III and IV.Methods:In this single center retrospective analysis (1991 - 2015) we included all patients with previously untreated AN who underwent single session LINAC or Cyberknife® based SRS with a minimum follow-up of 3 months. Patient data were analyzed and correlated (Pearson`s coefficient) with the different Koos grades in terms of radiological tumor control, preservation of serviceable hearing, course of median pure tone averages (PTA) and adverse events rated by Common Terminology Criteria for Adverse Events (CTCAE; v4.03).Results:301 patients (f:m = 151:150, median age 59 years ±13.6, range 17–84) were identified with a mean follow-up of 50.9 months (range 3–265). Mean tumor volume was 1.85 ml ±2.4 (range 0.1–23.7, the mean marginal dose was 12.4 Gy ± 0.8 (range 11–20) and the prescription isodose was 69.3 % ± 12.5 (range 32.9–86.2). With regard to the Koos classification 52 patients were considered as grade I, 162 as grade II, 42 and 45 as grade III and IV, respectively.At last follow-up after SRS 94% of the patients showed radiological tumor control. There was no significant correlation (p < 0.113) between Koos grades I/II vs III/IV and radiological tumor control.Median PTA of Koos I/II tumors increased about 49% (37,2 dB prior to SRS up to 55,6 dB at last follow-up). In case of Koos III/IV tumors the increase of median PTA was similar (47%; 46,2 dB up to 68,2 dB).The rate of transient facial nerve dysfunction CTCAE grade 1 or 2 in Koos I/II tumors was 2.3% and 4.6% in Koos III/IV. Permanent facial nerve dysfunction CTCAE grade 1 was observed in one patient with Koos grade I and III, respectively. Transient trigeminal nerve impairment CTCAE grade 1/2 occurred with 3.7% in Koos I/II and with 6.9% in Koos III/IV. Four patients (4.6%) with Koos III/IV tumors had permanent trigeminal nerve impairment CTCAE grade 1/2.Conclusion:SRS for AN shows reliable long term tumor control and a high rate of hearing preservation and without considerable permanent side effects. Therefore, SRS can be proposed as safe and effective treatment option for AN, even with higher Koos grades.

Hearing preservation after low dose linac radiosurgery for acoustic neuroma depends on initial hearing and time

PurposeTo assess long term outcomes and factors determining hearing preservation after low dose linac stereotactic radiosurgery (SRS) for acoustic neuroma (AN) at the Royal Adelaide Hospital using prospectively collected data. Material and methodsBetween 1994 and 2010, 102 patients had SRS for AN. Five patients had neurofibromatosis type 2, six sporadic cases had relapsed after surgery, and the remaining 91 sporadic cases had primary SRS. Dose was 12 or 14Gy. Sustained changes ⩾2mm in any diameter were deemed significant, and useful hearing was defined as inter-aural pure tone average (PTA)⩽50dB. Possible prognostic factors for hearing retention were tested by dividing the patients at pre-specified cutpoints: age (60years), maximum tumour diameter (20mm), initial PTA (20dB) and dose (12 vs 14Gy). ResultsEighty-four of the 91 sporadic primary SRS cases were evaluable for tumour control with at least one post-treatment MRI. Their median follow-up was 65mo (range 10–184mo). Eighty-two (97.6%) were controlled, the remaining two requiring salvage surgery for progression at 5.75 and 9.75years. Also, one of the post-operative cases required surgery at 2.1years after SRS. For the 50 sporadic primary SRS patients with initially useful hearing, median age was 56 (range 21–76), median initial PTA 16dB (range −11 to +45dB) and median tumour diameter 21mm (range 10–33mm). Four received 14Gy, the rest 12Gy. After SRS, 19 patients (38%) retained useful hearing. The Kaplan–Meier estimated preservation rate at 5years was 50% (95% CI 36–64%) but by 10years, this had fallen to 23% (95% CI 12–41%). On univariate analysis, the only significant factor was initial PTA (P<0.0001). The estimated risk of hearing loss after SRS for patients with initial PTA⩾20dB was 5.0 (95% CI 2.2–11.2) times that with PTA<20dB. ConclusionsTumour control was excellent (99/102=97% freedom from surgical salvage). Hearing preservation was strongly dependent on initial PTA, but there was a steady fall-off in hearing out to at least 10years.

Quality of Life in Patients Treated with Gamma Knife Stereotactic Radiosurgery for Acoustic Neuroma

To evaluate the impact of Gamma Knife Stereotactic Radiosurgery (GK) on the quality of life (QOL) in patients treated for acoustic neuroma (AN) using standard measures, and to correlate dizziness handicap inventory (DHI) scores with labyrinth radiation dose.

Predictors of hearing preservation after stereotactic radiosurgery for acoustic neuroma

Many patients with acoustic neuromas (ANs) have hearing function at diagnosis and desire to maintain it. To date, radiosurgical techniques have been focused on conformal irradiation of the tumor mass, with less attention to inner ear structures for which there was scant radiobiological information. The authors of this study evaluated tumor control and hearing preservation as they relate to tumor volume, imaging characteristics, and nerve and cochlear radiation dose following stereotactic radiosurgery (SRS) using the Gamma Knife. Seventy-seven patients with ANs had serviceable hearing (Gardner-Robertson [GR] Class I or II) and underwent SRS between 2004 and 2007. This interval reflected more recent measurements of inner ear dosimetry during the authors' 21-year experience. The median patient age was 52 years (range 22-82 years). No patient had undergone any prior treatment for the ANs. The median tumor volume was 0.75 cm(3) (range 0.07-7.7 cm(3)), and the median radiation dose to the tumor margin was 12.5 Gy (range 12-13 Gy). At diagnosis, a greater distance from the lateral tumor to the end of the internal auditory canal correlated with better hearing function. At a median of 20 months after SRS, no patient required any other additional treatment. Serviceable hearing was preserved in 71% of all patients and in 89% (46 patients) of those with GR Class I hearing. Significant prognostic factors for maintaining the same GR class included (all pre-SRS) GR Class I hearing, a speech discrimination score (SDS) >or= 80%, a pure tone average (PTA) < 20 dB, and a patient age < 60 years. Significant prognostic factors for serviceable hearing preservation were (all pre-SRS) GR Class I hearing, an SDS >or= 80%, a PTA < 20 dB, a patient age < 60 years, an intracanalicular tumor location, and a tumor volume < 0.75 cm(3). Patients who received a radiation dose of < 4.2 Gy to the central cochlea had significantly better hearing preservation of the same GR class. Twelve of 12 patients < 60 years of age who had received a cochlear dose < 4.2 Gy retained serviceable hearing at 2 years post-SRS. As currently practiced, SRS with the Gamma Knife preserves serviceable hearing in the majority of patients. Tumor volume and anatomy relate to the hearing level before radiosurgery and influence technique. A low radiosurgical dose to the cochlea enhances hearing preservation.

Long-term results of LINAC-based stereotactic radiosurgery for acoustic neuroma: The Greek experience

To estimate the value of LINAC-based stereotactic radiosurgery (SRS) for the long-term local control of unilateral acoustic neuromas. Twenty patients (median age 66; range 57-80 years) with unilateral acoustic neuroma underwent LINAC-based SRS from May 2000 through June 2004 with a dose of 11-12 Gy. The follow-up period ranged from 36 to 84 months (median follow-up period: 55 months). Before SRS none of the patients had useful hearing. The follow-up consisted of repeat imaging studies and clinical examination for assessment of facial and trigeminal nerve function at 6-month intervals for the first year and yearly thereafter. Eleven tumors (58%) decreased in size and eight (42%) remained stable. One tumor showed a minor increase in size on the MRI done 6 months after SRS in comparison with the pretreatment MRI; however, a subsequent decrease was noticed on the next radiographic assessment and the tumor remained stable from then on. None of the tumors increased in size in the long-term follow-up, thus giving an overall growth control of 100% for the patients in this study. None of the patients had useful hearing before SRS, so hearing level was not assessed during follow-up. No patient developed new, permanent facial or trigeminal neuropathy. LINAC-based SRS with 11-12 Gy provides excellent tumor control in acoustic neuroma and has low toxicity even after long-term follow-up.

Stereotactic radiosurgery for acoustic neuromas: a survey of the American Neurotology Society.

The purpose of this study was to better understand the complications, outcomes, and surgical difficulties in treating acoustic neuroma patients who have undergone stereotactic radiosurgery (SRS). A six-page, 28-item questionnaire was mailed to 395 members of the American Neurotology Society. The study was conducted through an academic neurotologic practice. Questionnaire respondents were neurotologic physicians in private and academic practice. A total of 46 patients who had undergone SRS were evaluated. Twelve (26%) of the 46 patients required microsurgery after SRS. Posttreatment cranial nerve status and the development of complications such as cerebrospinal fluid leak, meningitis, and cerebrovascular accident were evaluated. In the group of 12 patients who underwent microsurgery after SRS, 11 patients had some form of postoperative facial paralysis. Anacusis was present in all 12 patients. Two of the 12 patients had new-onset trigeminal neuropathy postoperatively. Microsurgical resection of acoustic neuroma after SRS is technically difficult. The difficulty exists regardless of the time of microsurgical resection after SRS. Patients who underwent microsurgery after SRS had uniformly poor cranial nerve results.

Failed stereotactic radiosurgery for acoustic neuroma

A case of recurrent acoustic neuroma in a 58-year-old man is presented. The tumour was initially subtotally removed and then was irradiated using stereotactic radiosurgery. He represented with ataxia and new onset headache four years later and underwent further surgery for recurrence of his acoustic neuroma. The literature is reviewed and the authors' view point on the different modalities of treatment is discussed.

Three-Fraction Stereotactic Radiosurgery for Treatment of Vestibular Schwannoma (Acoustic Neuroma) in Patients with Neurofibromatosis Type 2

Neurofibromatosis type 2 (NF2) patients risk complete deafness from either bilateral vestibular schwannoma (VS) or its treatment. Both microsurgical resection and Stereotactic radiosurgery (SRS) have been associated with poorer rates of hearing preservation in patients with NF2 than in sporadic VS. In an attempt to maximize hearing preservation while maintaining good tumor control, we have conducted a prospective trial of three fraction SRS for the treatment of VS in patients with NF2. Eleven VS in 10 patients with NF2 were treated. Conventional frame-based Stereotactic localization was used. Mean maximal tumor diameter was 19.5 mm (range 11–28). A total dose of 21 Gy was administered in 7 Gy fractions with a mean interfraction interval of 12 hours. Patients were evaluated with neurologic examination, MRI, and audiometry. No patients were lost to follow-up. One patient died due to complications following surgical resection of a contralateral VS. Tumor (10–46 months posttreatment, mean 26 months) was stable or decreased in 9 of 10 tumors (90%). One patient experienced slight tumor enlargement at 27 months, which subsequently regressed. Actuarial rate of hearing preservation at 2 years was 67%. All patients (n = 5) with good pretreatment hearing (Gardner–Robertson grade 1 or 2) had preserved useful hearing (grade 1–3) at 1 year. Two patients (grade 3 and 4 hearing) lost all hearing within 24 hours of treatment; another patient with grade 3 hearing lost residual hearing over 6 months. One patient developed facial spasms. Three-fraction SRS for acoustic neuroma is well tolerated in patients with NF2 and is associated with a lower risk of hearing loss and other cranial neuropathy than single-fraction treatment. Continued follow-up will be necessary to evaluate long-term tumor control and hearing preservation.

Stereotactic radiosurgery for acoustic neuroma: a Canadian perspective.

Stereotactically delivered radiation is now an accepted treatment for patients with acoustic neuroma. In some cases, patient preference may be the reason for its selection, while in others neurosurgeons may select it for patients who are elderly or have significant risk factors for conventional surgery. The majority of patients with acoustic neuroma treatment with stereotactic radiosurgery have been treated with the Gamma Knife, with follow ups of over 25 years in some instances. Other radiosurgery modalities utilizing the linear accelerator have been developed and appear promising, but there is no long-term follow up. Canada does not possess a Gamma Knife facility, and its government-funded hospital and medical insurance agencies have made it difficult for patients to obtain reimbursement for Gamma Knife treatments in other countries. We review the literature to date on the various forms of radiation treatment for acoustic neuroma and discuss the current issues facing physicians and patients in Canada who wish to obtain their treatment of choice.

Three-fraction stereotactic radiosurgery for acoustic neuroma

Three-fraction stereotactic radiosurgery for acoustic neuroma

Linear accelerator-based stereotactic radiosurgery for acoustic neuromas

Linear accelerator-based stereotactic radiosurgery for acoustic neuromas

Volume growth rate of acoustic neuromas on MRI post-stereotactic radiosurgery

Of the approximately 160 acoustic neuroma patients treated with stereotactic radiosurgery in the world up to 1987, 8 patients at UCLA Medical Center have had two or more magnetic resonance scans at least one year apart available for study (all 8 patients were treated with stereotactic radiosurgery for acoustic neuromas by the Department of Neurosurgery at the Karolinska Hospital, Stockholm, Sweden). The followup time after radiosurgery ranged from 4 to 8 years. The volume doubling rate post-stereotactic radiosurgery was calculated to be slow (763 to 888 days) in two patients, virtually arrested in five patients (doubling times larger than 2500 days) and negative (−563 days) in one patient indicating a shrinking tumor. Due to the limited sample size no radiological finding or clinical data correlated with the volume doubling times. A control patient that had no treatment for her tumor had a doubling time of 217 days for comparison.